Prevailing usage of the telephone system requires the implementation of more automatic facilities that enable the subscriber to maximize utilization of the telephone system in conjunction with diverse automatic equipments with a minimum degree of human intervention. Various facilities are available to automatically couple called subscriber equipments to the telephone line. One such commonly used facility is the telephone answering and recording device which is automatically coupled to the telephone line by transmission of a predetermined number of ringing signals. In one of these systems, as shown in U.S. Pat. No. 4,049,916, issued Sept. 20, 1977 to D. W. Danner, ringing signals impressed on the usual tip and ring leads are subsequently detected and applied to operate a first optical isolator to generate a series of pulses which operate a counter. Upon registering a predetermined count, the automatic answering and recording device is operated to provide an announcement or instruction message followed by the actuation of a recording device to record the calling party's message. A second optical isolator circuit is used to monitor a C-lead from the telephone central office. If a message has been recorded, and the subscriber goes off-hook, the monitored condition of the C-lead is used to control the operation of a tone signal generator which is effective to impress a distinctive tone signal on the subscriber's line apprising the subscriber that a message is recorded in the answering equipment.
In other automatic telephone connect systems, a speakerphone may be connected to a telephone loop circuit without the calling parties going off-hook. One such system is exemplified by U.S. Pat. No. 3,041,411, issued June 26, 1962 to D. C. Beatty, wherein receipt of a ringing signal connects a microphone and a speaker to the telephone circuit for a predetermined time set by a number of capacitors. If sound carrying electrical surges are not impressed by the speaker on the loop, the speaker microphone is automatically disconnected. Further, this system may be disconnected whenever the calling party replaces their telephone handset to the "on-hook" position. An interrupt may also be initiated by the called party depressing a push button control switch.